Method and apparatus for continuously forming a fibrous web from a liquid suspension and progressively removing liquid therefrom



Apnl 1, 1958 s. E. SEAMAN 2,828,675

METHOD AND APPARATUS FOR CONTINUOUSLY FORMING A FIBRCUS was FROM ALIQUID SUSPENSION AND PROGRESSIVELY REMOVING LIQUID THEREFROM Filed Feb.21, 1956 s Sheets-Sheet l INVENTOR 57WAET F. SEAMAN.

ATTORNEY Aprll 1958 s. E. SEAMAN 2,828,675

METHOD AND APPARATUS FOR CONTINUOUSLY FORMING A FIBRJUSWEB FROM A LIQUIDSUSPENSION AND PROGRESSIVELY REMOVING LIQUID THEREFROM Filed Feb. 21,1956 3 Sheets-Sheet 2 INVENTOR yin A7 6 56/: M14

ATTORNEY Apnl 1, 1958 s. E. SEAMAN 2,828,675 A METHOD AND APPARATUS FORCONTINUOUSLY FORMING A FIBROUs WEB FROM A LIQUID SUSPENSION ANDPROGRESSIVELY REMOVING LIQUID THEREFROM Filed Feb. 21, 1956 5Sheets-Sheet 3 ATTORNEY Unite States Patent "Office 2,828,675 PatentedApr. 1, 1 95 8 METHOD AND MPARATUS FOR CONTINUOUS- LY FONG A FIBRGUS WEBFROM A LIQUID SUSPENSEQN AND PROGRESSIVELY REMOV- lNG LIQUID THEREFRQMStewart E. Seaman, White Plains, N. Y.

Application February 21, 1956, Serial No. 566,844

13 Ciaims. (Cl. 92-38) This invention relates to the art of forming asubstantially uniform web or mat of fibrous material from a liquidsuspension of fibers, and is useful, for example, in the manufacture ofboard and the like from fibers such as ground wood, pulp, cottonlinters, bagasse, straw, etc. It is also useful in the manufacture ofchemical pulp and in the production of alkali cellulose to control theratio of alkali to cellulose in the alkali cellulose.

One of the principal objects of the invention is to provide a way toform a web continuously from a suspension of fibers and mechanically tocompact and firm the web and remove the maximum amount of liquidtherefrom in a less expensive operation and with less expensiveapparatus than has heretofore been required.

The conventional way to form such a webhas been to cause a deposit offibers from suspension upon a moving perforate or foraminous backingsuch as a cylindrical mold or a Fourdrinier wire, suflicient liquidbeing removed therefrom while on such backing to produce a web of lowconsistency, after which the web in this weak condition is deliveredupon a traveling felt and passed between press rolls, the liquid contentbeing progressively reduced until the desired consistency is reached.Suction boxes underneath the Fourdrinier wire augment gravity in theremoval of liquid and a couch roll at the end of the wire just beforedelivery to the felt exerts opposing pressures upon the web andexpresses liquid to perhaps a consistency of 25%, the consistency beingraised to around 40% in the press rolls, after which in the making ofboard the drying of the web is completed in a steam heated dryer.

A specific objective of the present invention is to dispense with thecostly wet end, Fourdrinier wire and felt in the production of fiberwebs from suspension. Another object is to reduce the size and floorspace requirements of apparatusfor the purpose. Still other objects willappear as the description proceeds. j

In accordancewith this invention, the web is preliminarily formed on astationary member which is in the form of a smooth perforate platedisposed at an inclination so that the stock material will flow downover the plate by gravity, being meanwhile sulficiently dehydrated bythe escape of liquid through-the perforations to cause the fibers to bedeposited upon the plate and mat into a more or less uniform web.

' Preferably the web moves from this plate on to a comparatively shortforaminous conveyor and while it is car} ried on this conveyor it iscompressed and somewhat firmed and further dehydrated by passing throughsuccessive rollers of progressively increasing pressure.

The conveyor delivers the web directly without the use offelt into thenip or bite of press rolls which complete the mechanical dehydration.The lower roll is so constructed that the liquid expressed from the webescapes through the periphery of the roll, thereby avoiding theformation of a pool of liquid at the bite and the creation of anhydraulic pressure in the web counter to its movement and the consequentrupturing of the web, as would the plate 10 is set according to the typeand consistency.

otherwise be likely to occur in the absence of a felt toabsorb theliquid.

In its commercial form the contact surface of the roll is made up of aseries of closely spaced rings which are internally mounted upon andsupported by axially extending bars on spokes which radiate from hubsfixed at spaced intervals upon an axial drive shaft. The expressedliquid escapes through the spaces between the rings.

Preferably there are two such lower rolls which have pressure engagementwith a single top roll, and the top roll may be solid roll or it too maybe made up of spaced rings. The press rolls may comprise two or morepairs instead of a three-roll construction, and in either form thepressure of the lower rolls is adjustable and in operation the pressureupon the web progressively increases as it passes through the pressrolls.

The surface of the rolls may be smooth or it may be serrated. In thelatter case the surface of the rings will be peaked or saw toothed incross section and the surface of the top roll will be serrated andcomplementary to that of the lower rolls.

Preferably the rings are tapered on their sides so as to provide annularintervening spaces of increasing width that will afford relief for thefibers that drain off with the liquid and avoid clogging. In such caseintervening spacing plates will be similarly tapered.

The invention comprehends other features of construction and has otherobjects and advantages as will appear from the following description ofthe embodiment of the invention illustrated in the accompanying drawingsto which reference is now made.

Fig. 1 is a diagrammatic side view of an apparatus embodying theinvention;

Fig. 1A is a fragmentary face view of a portion of the inclinedperforate plate;

Fig. 2 is a diagrammatic side view of the press roll portion of theapparatus showing the rollers in end'view and the pressure adjustingmeans for the lower rolls;

Fig. 3 is an enlarged side elevation of one of the lower rolls with someof the rings removed and one ring shown in section and in position to beadded;

Fig. 4 is a perspective of a spacing plate and of the attaching pinsshown spaced from the plate;

Fig. 5 is a fragmentary section of a portion of a bottom roll having asmooth surface and taken on line 5-5 of bottom roll andof the mating toproll showing serrated mating faces and taken on a 10-40 of Fig. 7. V

The apparatus, as shown in Fig. 1, includes a'smooth inclined plate 10which is perforated, as shown in Fig.

line corresponding to line lA,'with holes of a predetermined sizeandspacing, and

which is disposed with its upper end in position to reccive stock from ahead box and stock regulator 11. The stock is a liquid suspensionoffiber such as ground wood, pulp, cotton linters, alkali cellulose, etc.,the consistency of which is controlled and the inclination of of thestock. With wood pulp, for example, the con sistency' would beapproximately 1 /2% and at the bottom of the incline the consistencywould be 5 or 6fpercent. a e 7 At its lower end the plate 10 delivers onto a horizon tal foraminous endless conveyor 12 which runs, over pulleys13 one of which is driven. Below and in contact with the top run of theconveyor are a series of three rollers 14 which are respectively opposedby three rollers 15 on the top of the conveyor. Theserollers are drivenand the pressure exerted by the pairs of rollers progressively increasesso that at the end of the conveyor the web is substantially firm and theconsistency is 12 to 15 percent.

From the conveyor 12 the web passes into the bite of press rolls indirect contact with the rolls without the interposition of felt, thebottom roll being so constructed as to receive and dispose of theexpressed liquid in a direction normal to the web as will be explainedhereinafter.

The web will be subjected to two successive pressings by the pressrolls, the pressure on the second pressing being greater than that onthe first pressing. This may be done by two pairs of press rolls or, asshown in Fig. 1, two bottom rolls 16 and 17 may coact with one top roll18. In the latter case the top roll is preferably larger than the bottomrolls, being, for example, from twentyfour to thirty inches in diameterand the bottom rolls being of the same or approximately the same sizefrom eighteen to twenty-four inches in diameter.

The conveyor 12 is preferably disposed with its top run above the levelof the bite of rolls 16 and 18 and so as to deliver the web as close aspossible to the bite. The web is firm enough to enter into the bitewithout rupture and it is further firmed and dehydrated as it passesbetween rolls 16 and 18. it is then strong enough to pass into the bitebetween rolls 17 and 18 the pressure of which is greater than that ofrolls 16 and 18. The liquid expressed by the press rolls passes bygravity down through the lower rolls and the web is led from the pressrolls on to an endless conveyor 19 which may be foraminous and runs overpulleys 20 one of which is driven. From the conveyor 19 the web goes toa dryer or to a picker if it is to be used at once.

The press rolls are power driven and the pressures will be regulated soas to complete the dehydration to a consistency of from fifty to sixtypercent. Fig. 2 illustrates a mounting for the lower rolls 16 and 17which enables the obtaining of the desired differential pressures. Roll16 bears in a pair of arms 21 (one being shown) and roll 17 bears in apair of arms 22 (one being shown). These arms have a common pivot 23 attheir inner ends and their outer ends are pivotally con nected to theends of the piston rods 24 and 25, respectively, of pneumatic loadingcylinders 26 and 27, respec tively, these cylinders having pivotalattachment to feet on axes parallel to those of the connections of thearms to the piston rods. The cylinders are independently controlled andconstitute independent power means for adjusting the bearings of theshafts of rollers 16 and 17, thereby independently adjusting thepressures of the bottom rolls with respect to the top roll. The pressureexerted on the outer ends of the arms is regulatable and is set so thatthe pressure of roll 17 exceeds that of roll 16. I

The liquid which is drained or expressed from the web during itsdehydration is caught in a tank or pan 28 and provision is made toreturn this to the machine chest from which the stock is fed to the headbox 11 or to pass it to dialyzers for purifying before returning to themachine chest.

As shown the tank is partitioned'into sections. The first sectioncatches the dripping from plate 10 and conveyor 12 and runs into abottom header 29 from where it is pumped by pump 30 through pipe 31tothe machine chest. A second section of tank 28 catches the liquid fromthe first press roll 16 and a third section catches the liquid from thesecond press roll 17. These sections discharge into drain pipes whichhave valves 32 and 33,

respectively, which in one position pass the liquid down into header 29and in another position direct the liquid to pipes 34 and 35,respectively, which lead to dialyzers.

The construction of the two bottom rolls 16 and 17 is shown in Figs. 3to 11, inclusive. They are composed of a series of rings which arespaced slightly so as to allow the expressed liquid to pass between theminto the hollow interior of the rolls and to drain therefrom into thetank 28. These rings may have a smooth cylindrical surface or they maybe peaked or in the form of a salient angle in cross section to increasethe surface area. Their sides are preferably undercut or bevelledinwardly to avoid clogging.

The rings are strongly internally braced in view of the considerablepressure ,to which they are subjected. Wheel-like structures are fixedat intervals along an axial drive shaft and bars on the fellies at theouter ends of the spokes extend axially and the rings are fitted overthese bars and are supported by them. Alternate bars carry spacingplates which fit between the rings and are pinned to their sides.

The rings 40 shown in Fig. 3 have a smooth cylindrical peripheralsurface and a series of such rings are disposed in spaced relation onthe inner structure of the roll. This inner structure has an axial driveshaft 41 and at spaced intervals wheel-like structures 42 are keyedthereon. These have a hub portion 43, a series of radial spokes 44 and afelly 45. On the fellics are a series of axial bars which tie the wheelfellies together. As shown, there are eight spokes and eight bars setinto grooves in the fellies; one opposing each spoke. Four of these bars46 are attached to the fellies by screws and have arcuate outer faces onwhich the rings fit. These bars 46 are equally spaced and oppose fouralternate spokes. Between the bars 46 and opposing the intermediatespokes are plate supporting bars 47 which also have arcuate outer facesfitting within the rings. These bars 47 are secured to the fellies, asby screws, and they are provided with transverse slots 48 into which fitthe inner ends of spacing plates 49 that are disposed between the rings.

As shown particularly in Fig. 5, the rings have their sides tapered orbevelled, the inner axial dimension being less than the outer thusreducing the tendency of fibers carried by the expressed liquid fromclogging in the spaces between the rings. The rings have two throughholes radially opposite each plate 47 and pins 50 are carried by .theplates 49 and project equally on opposite sides of the plate and enterhalf way into the through holes in each adjacent ring. The plates areshaped to fit into the tapered space between the rings.

The rings are clamped against longitudinal shifting on the bars by endclamping rings 55, one of which is shown in Fig. 6, which are secured inclamping position by lock collars 56. The spacing between the rings willusually be one-sixteenth of an inch or less.

Instead of smooth face rings, they may be peaked as shown in Fig. 10 andform a corrugated surface for the roll cooperative with a complementarycorrugated surface of the top roll with the resultant greater surfacearea and increased yield.

The top roll 18 may be a solid face roll or it too may have spacedcircumferential slots to receive the expressed liquid.

For vsome materials the pressure of the two bottom rolls may be thesame.

What is claimed is:

1. The method of forming a web of fibrous material from a stockconsisting of a liquid suspension of fibers, said method comprisingcontinuously flowing the stock in a uniform sheet upon a stationaryinclined perforated plate having a smooth surface and causing the sheetto slide downwardly upon said surface by gravity at a speed to drainsufiicient liquid therefrom through the perforations during the downwardmovement to form a web of the fibers, causing the web so formed toprogress continuously and subjecting the web as it progresses topreliminary opposing pressures sulficient to compact the web and expressliquid therefrom and partially dehydrate the web, and continuing themovement of the partially dehydrated Web and subjecting it to finalopposing pressures substantially greater than the preliminary pressuresand completing the desired dehydration and conducting the liquidexpressed from the web during such greater pressure from the web in adownward direction normal thereto.

2. The method defined in claim 1 in which there are a plurality ofgradually increasing preliminary opposing pressures.

3. The method defined in claim 1 in which there are a plurality ofprogressively increasing final pressures.

4. The method of forming a web of fibrous material from a stockconsisting of a liquid suspension of fibers, said method comprisingcontinuously flowing the stock in a uniform sheet upon a stationaryinclined perforated plate having a smooth surface and causing the sheetto slide downwardly upon said surface by gravity at a speed to drainsufiicient liquid therefrom through the perforations during the downwardmovement to form a web of the fibers, continuously progressing the webso formed and subjecting it to opposing pressures sufficient to expressliquid therefrom to a desired consistency and conducting the liquidexpressed therefrom by such opposing pressures from the web in adownward direction normal thereto.

5. An apparatus for forming a web of fibrous material, comprising aninclined perforate stationary plate having a smooth surface and adaptedto have fiber suspension stock which is delivered to its top end flowdown its said surface by gravity and partially drain the liquidtherefrom and allow fibers in suspension to mat thereon, and press rollspositioned to receive the web so formed into their bite, the bottom rollbeing hollow and formed of a plurality of spaced rings.

6. An apparatus for forming a web of fibrous material as defined inclaim 5 in which the bottom roll comprises an axial drive shaft, aplurality of spoke bearing hubs fixed on the shaft in spaced relation,bars on the ends of the spokes extending parallel with the shaft, and aplurality of spaced rings fitting over and secured to the bars.

7. An apparatus as defined in claim 6 together with spacing platesbetween successive rings supported by certain of said bars and securedto the lateral face of an adjacent ring.

8. An apparatus as defined in claim 5 in which the press rolls comprisea top roll and two bottom rolls successively contacting the top roll,each bottom roll being hollow and formed of a plurality of spaced ringsand having an axial drive shaft mounted in adjustable bearings, togetherwith an independent power means for adjusting the bearings of eachbottom roll shaft and thereby independently adjust the pressures of thetwo bottom rolls with respect to the top roll.

9. An apparatus as defined in claim 5 in which the externalcircumferential face of the rings is peaked in cross section, wherebythe rings collectively make a serrated cylindrical surface, and in whichthe top roll has .a complementary serrated cylindrical surface.

10. An apparatus as defined in claim 7 in which the sides of the ringsconverge inwardly and the spacing plates are tapered to fit betweenadjacent rings.

11. An apparatus for forming a web of fibrous material, comprising aninclined perforate stationary plate having a smooth surface and adaptedto have fiber suspension stock which is delivered to its top end flowdown its said surface by gravity and partially drain the liquidtherefrom and allow fibers in suspension to mat thereon, a travelingforaminous conveyor disposed at the bottom of the plate in position toreceive the web therefrom, and press rolls positioned to receive the webfrom the conveyor into their bite, the bottom roll being hollow andformed of a plurality of spaced rings.

12. An apparatus as defined in claim 11 together with at least one pairof rollers disposed in opposition on opposite sides of the conveyor andadapted to compact and express liquid from the web on the conveyorpassing between the rollers.

13. An apparatus as defined in claim 12 in which there are a pluralityof pairs of rollers disposed in succession along the conveyor and inwhich the rollers of the successive pairs are progressively disposed ingreater pressure relation.

References Cited in the file of this patent UNITED STATES PATENTS923,870 Meader June 8, 1909 990,950 Barber May 2, 1911 1,493,536 HaugMay 13, 1924 1,503,605 Shaw Aug. 5, 1924 1,553,463 Nishina Sept. 15,1925 2,209,756 Berry July 30, 1940 2,488,700 Bidwell Nov. 22, 1949

11. AN APPARATUS FOR FORMING A WEB OF FIBROUS MATERIAL, COMPRISING ANINCLINED PERFORATE STATIONARY PLATE HAVING A SMOOTH SURFACE AND ADAPTEDTO HAVE FIBER SUSPENSION STOCK WHICH IS DELIVERED TO ITS TOP ENF FLOWDOWN ITS SAID SURFACE BY GRAVITY AND PLURALITY DRAIN THE LIQUIDTHEREFROM ANS ALLOW FIBERS IN SUSPENSION TO MAT THE BOTTOM A TRAVELLINGFOAMINOUS CONVEYOR SIDSPOSED AT THE BOTTOM OF THE PLATE IN POSITION TORECEIVE THE WEB THEREFORM, AND PRESS ROLLS POSITIONED TO RECEIVE THE WEBFROM THE CONVEYOR INTO THEIR BITE, THE BOTTOM ROLL BEING HOLLOW ANDFORMED OF A PLURALITY OD SPACED RINGS.